International Publication No.: WO 01/28284
International Application No.: PCT/JP00/07169 Oct. 16, 2000
International Application Date: Oct. 16, 2000
Priority No.: Japanese Patent Application No. 11-294223
Priority Date: Oct. 15, 1999 Oct. 15, 1999 JP
1. Technical Field
This invention relates in a sound collector, and it is related to the sound collector that the most suitable microphone characteristics are set up corresponding to the use environment.
2. Description of the Related Art
So far, accessory microphone to choose to have the most suitable microphone characteristics corresponding to the use and the sound collection object is known. The types of such accessory microphone include a desktop type, a built-in type, a hand type, and so on. Functionally, a non-directional type and a single directive type are known. Also, a microphone that may be switched between a standard microphone and a long distance microphone is known. In view of the form of microphone, a vocal type, a stand table type and a clip type are known. Various microphones stated above have been used corresponding to the feature and usage as conventional accessory microphones.
However, the above-mentioned conventional accessory microphones were not suitable for collecting sound from the specific direction. This is because the conventional accessory microphones could not limit directivity on the beam toward the sound collection object. Further, it wasn""t possible to change a use of microphone that was used for a specific use. For example, when a microphone used for conferencing was put in the open air, it was a problem that an ambient noise was taken and that aural recording wasn""t done well. To dissolve the above-mentioned problem, it is an object of this invention to provide a sound collector that may change the characteristics of the microphone so that it may achieve the most suitable microphone characteristics corresponding to the use environment of the microphone.
To solve the problem, a sound collector of this invention is collecting sound by changing directivities of microphone according to an environment in which a sound collection object is located; wherein the above microphone is an optical microphone that comprises a diaphragm to vibrate by the sound pressure; an illuminant to irradiate an optical beam to the above diaphragm; a photodetector which receives a reflection light of the light beam irradiated in the diaphragm and which outputs a signal which copes with the oscillation of the diaphragm; an illuminant drive circuit to drive the illuminant to supply predetermined electric current; and a negative feedback circuit that supplies the signal outputted by the optical detector to the illuminant drive circuit as a negative feedback signal; and wherein the gain of negative feedback of the negative feedback circuit is changed corresponding to the environment. Another sound collector of this invention further comprises means for distinguishing a spectrum of the voice from the sound collection object or the noise, wherein the environment in which the above sound collection object is located can be decided based on the recognition. Still another sound collector of this invention may execute the recognition of the spectrum at the arbitrary timing.